【作者】 黎荣；

【导师】 王金诺；

【作者基本信息】 西南交通大学 ， 机械设计及理论， 2006， 博士

【摘要】 产品的设计阶段决定了70%以上的产品生产制造成本,因而在产品设计过程中,尽可能早地考虑到产品的可制造性和经济因素能有效提高产品质量,降低返修率和报废率。 造成目前产品开发活动效率不高的根本原因是设计者缺乏广泛的制造知识,由经验支配的产品设计方式是生产技术更新的致命伤。概念工艺规划系统的主旨是完成并行工程早期概念设计的可制造性评价和制造成本估计。通过概念工艺规划系统能实现零件材料的选择、制造工艺的确定、制造资源的选择和制造成本的估计,因此可有效地避免和减少出现设计好的产品由于可制造性差导致的难以制造、甚至无法加工的情况,从而规避了产品设计主体修改和彻底返工。 鉴于目前国际学术界对概念工艺规划系统的研究还处于起步阶段,绝大多数原型系统无法获取完整、有效的零件信息,缺乏合理的零件形状及特征描述。本文重点进行以下几方面的研究: 1) 在产品生命周期建模技术的支持下,分析支持并行工程的概念工艺规划系统的研究意义,探讨国内外目前概念设计和概念工艺规划系统的研究现状。在对目前概念工艺规划系统所存在主要不足的认识基础上,提出了所构建概念工艺规划系统的信息模型、活动模型及体系结构; 2) 在对UG实体/特征模型进行深入探讨的基础上,研究零件模型相关信息的提取技术。运用UG二次开发工具和Visual C++6.0 Windows编程工具,编制设计零件模型信息提取接口,从UG的CAD数据库中提取概念工艺规划系统所需的零件各层次结构信息,非结构化工艺、管理信息,并将其保存在SQL Server 2000搭建的零件模型信息库中; 3) 研究目前特征建模系统中广泛存在的特征有效性维持问题,将特征识别技术与基于特征设计技术相结合,分析特征相交的各种形态,运用增量式特征识别映射技术,编制铣、钻类制造特征概念工艺规划系统的零件外形表述及制造特征识别映射接口程序; 4) 根据所获取的零件设计属性信息,基于层次等价关系进行零件层次上的模型比照:基于从UG的CAD工程数据库中提取出的完整零件结构信息,编制算法和程序,进行新建设计零件和零件库中已有模板零件的相似性评更多还原

【Abstract】 One analysis shows that at least 70% of the product’s final costs are set by the decisions made during the design stage. This implies that once a final design is completed, there is little opportunity to reduce the product cost since a significant portion of its cost has already been determined. Base on this fact, companies strive to consider economic factors as early as possible in the design process.Lack of manufacturing knowledge among designers is considered the main cause of the current inefficient product development process. An experienced designer repeatedly chooses the manufacturing process he/she is familiar with, without considering alternative processes and material. This is harm to improvement of the technique of production. Conceptual process planning (CPP) is an activity of cost preliminary manufacturability assessment of conceptual design in the early product design stage. It aims at determining manufacturing processes, selecting resources and equipment, and estimating manufacturing costs roughly. Conceptual process planning supports product design to optimize product form, configuration, and material selection and to minimize the manufacturing cost.There are a lot of researches related to process planning of detail design including the development of various CAPP systems for machined parts. However, there has been relatively little work done in the area of CPP. Most of the present prototype system of CPP is short of the essential, efficient part information and the reasonable description of shapes and features. So this research focuses on the following specific problems:1) The significance of studying CPP is analyzed. Some important research activities that have made major contributions to the development of conceptual design and CPP are reviewed. Based on the insufficient analysis of the existing CPP, a new architecture of CPP including its information model and activity model are presented;2) The technique of extracting part and feature information based on UG solid models is studied. The interface of information extraction is established supported by the UG/Open API and Visual C++ 6.0. The required informationof CPP, such as hierarchical part data, technology and management data, are stored in the database of the part model established by SQL Server 2000;3) Investigating the validity maintenance in the feature modeling. Based on the feature recognition and design by feature to analyze the interaction between features. The feature mapping interface of CPP about manufacturing features of milling and drilling is programmed by incremental feature recognition and conversion technology;4) According to the design attributes of the part, the model’s similarity of part layer is compared based on hierarchical equivalence relation. Based on the complete information of part geometry and feature, the similarity assessment interface of part geometry and feature is programmed. The outputs of the similarity assessment interface are similarity degree and compatible features. The significance of this research is not restricted in CPP. For the processplanning of detail design and CAPP, the critical technique studied in this research, such as how to extract the complete information of part from CAD models, how to realize the primary model-design models map to application models, how to carry through the similarity assessment of part models, are important to search and extraction of similar parts, similar technologies and analysis of manufacturability and cost estimation.更多还原